There are lot of Visio stencils already available provided by Microsoft; As I am new to Visio I am not much aware of the Oracle hardware stencils, however, you can create new Visio stencils for your requirement if it is not existing:
1. On the File menu, point to Shapes, and then click New Stencil.
2. To save the stencil, right-click the stencil title bar, and then click Save.
3. Type a name for your stencil, and then click Save.